In a conventionally known shirring machine, in, for example, a sleeve shirring step, a sewing length is determined by manually measuring the circumference of an arm hole and the periphery of the sleeve separately, then the sewing length is divided into several portions to define sewing areas, number of stitches and amount of shirring from the start to end of sewing in correspondence to each sewing area of a work piece having these sewing areas are stored in a memory, the stored data are read in synchronism with the reciprocating motion of a sewing needle of the machine from the start to end of sewing, and the amount of shirring of the work feeder is changed according to the data read from the memory (Japanese Utility Model Public Disclosure No. 55974/84 Official Gazette).
However, the conventional shirring machine, in which the circumferences of the arm hole and the sleeve were measured separately by hand to determine the sewing length, had various disadvantages that troublesome operations and time consuming calculations were required to input the data such as the number of stitches and the amount of shirring to the memory, bulging at the upper end of the sleeve is made unnatural because the amount of shirring is uniform for each sewing area, much experience is necessary for making the data because the amount of shirring changes by the quality of the cloth and the cutting angle, and the quality of the finished product varies dependent upon the data made as described above.
Accordingly, an object of the present invention is to provide a shirring control apparatus adapted to automatically read sewing data (sewing length that is the number of stitches, and differential movement necessary to join a body cloth and a sleeve cloth) contained in a pattern.
Another object of the present invention is to provide a shirring control apparatus adapted to automatically calculate the sewing data from the data read automatically.
A further object of the present invention is to provide a shirring control apparatus adapted to divide the circumference of the sleeve into a desired number of areas from the calculated sewing data and to distribute the amount of shirring to the areas.
A further object of the present invention is to provide a shirring control apparatus adapted to control the amount of shirring in these areas for each stitch.
A further object of the present invention is to provide a shirring control apparatus adapted to adjust the amount of shirring controlled for each stitch by correcting the amount of the differential movement dependent upon the quality of the cloth and the bias.
A still further object of the present invention is to provide a shirring control apparatus adapted to display the amount of difference in the amount of feed between the upper feed teeth and the lower feed teeth in shirring.